Features allow you to define parts of the model that can be unlocked by an individual customer.
For example, this is useful for defining any BETA features that will not be visible to a customer unless he turns such a feature ON. In the case of large "package" projects with many different customers you can use it to divide your application into features that individual customers can turn on or off.
Features are always turned on at the system level. If you need to allow a specific functionality per user you need to use the correct Authorization.